1. Field of the Invention
The present invention relates to an imaging system, and in particular, relates to a camera platform system that can remotely drive a zoom/focus/tilt/pan and the like.
2. Description of the Related Art
Conventionally, an imaging system (virtual studio system) for acquiring a composite image in which a photographed image is synthesized with a computer graphic (hereinafter referred to as “CG”) image is well known. In the virtual studio system, a CG image, which is the background (or foreground) of a photographed image, needs to be changed in accordance with the motion of the photographed image. A camera serving as an imaging apparatus for obtaining a photographed image is mounted on a remote control camera platform that remotely controls panning for rotating the direction of the camera in the left and right direction, or tilting for rotating the direction of the camera in the up-and-down direction (pan/tilt), and zoom/focus of a lens. Furthermore, a camera platform system constituted by a camera, a lens, and a remote control camera platform together with an operation device for remotely controlling these components and an image synthesizing system for synthesizing a photographed image with a CG image form a virtual studio system. Separately from pan/tilt position information about the camera and zoom/focus position information about the lens, a photographed image captured by a camera is transmitted from the camera platform system to the image synthesizing system. The image synthesizing system generates a composite image in which a CG image (signal) is changed in accordance with the timing of the transmitted photographed image (signal), based on the photographed image (signal) transmitted from the camera platform system and information about the positions of the camera and the lens.
In this context, as a device for synchronizing the timing between a photographed image (signal) and a CG image (signal), Japanese Patent No. 3478740 discloses an imaging system that includes a lens device having a function of outputting position information using an encoder. Also, Japanese Patent Laid-Open No. 11-112856 discloses an image capturing apparatus that includes an operation unit provided with an operation device which shows the current position based on an instructed position signal by taking into account the delay factor of the drive units of the remote control camera platform.
However, in the imaging system employing an encoder, the encoder is disposed on the side of the lens device, a position detection mechanism such as an encoding counter or the like needs to be provided separately on the side of the image forming system, resulting in an increase in the size and the production cost of the apparatus. Also, when the imaging system is applied as a camera platform system, a lens to be mounted needs to have a position detection mechanism, and thus, the model of a lens that can be mounted in a remote control camera platform is limited.
On the other hand, in the apparatus that takes into account the delay factor of the drive units of the remote control camera platform, such an apparatus would be greatly affected by transmission delay when a long distance between the operation device and the remote control camera platform exists in the case of, for example, golf broadcast or when the apparatus is adopted into a system that is connected thereto via other equipment. In particular, in the case of establishing a connection using a public line where delay time is not constant, a change in delay time may greatly affect on the accuracy of a position signal. Furthermore, in a system in which a connection is established by switching an operation device and a plurality of remote control camera platforms such as in a sport (golf, baseball, etc.) broadcast or the like, the operation device needs to recognize information about the delay amount of all of the remote control camera platforms, resulting in a more complex configuration.
As described above, in an imaging system employing a conventional remote control camera platform, an expensive machine and a complex transmission path need to be constructed in order to synchronize a photographed image and a CG image, whereby the construction of an imaging system is necessitated depending on a desired utilization, resulting in a poor general applicability.